fentanyl versus midazolam as additives to bupivacaine in ultrasound guided transversus abdominis plane block

Conditions: Postoperative Pain

Summary: pain triggers a complex biochemical and physiological stress response leading to impairment of pulmonary, immunological and metabolic functions. the transversus abdominis plane (tap) block, is a regional anaesthesia technique used for various surgeries through the lower to mid-abdominal wall.the addition of fentanyl to the local anaesthetic in ultrasound-guided tap block prolongs the analgesia, lowers postoperative pain, and decreases the opioid consumption. adding midazolam as a bupivacaine adjuvant for tap block reduces the 24-h morphine consumption extends the postoperative analgesia duration. the aim of the work is to study the effect of the addition fentanyl and midazolam on the onset, duration of the analgesic effect of tap block intraoperative fentanyl consumption, time for first rescue analgesia. in patients undergoing simple unilateral abdominal surgeries.

informed written consent will be obtained from study participants or their legally authorized representative. this is a randomized controlled double blinded study; patients will be enrolled in the study and will be randomized and equally divided into three groups: group a: (tap block with 20 ml of bupivacaine 0.25% and 50 μ g of fentanyl) group b: (tap block with 20 ml bupivacaine 0.25% and 50 μ g /kg midazolam) group c: (tap block with 20 ml bupivacaine 0.25% only). induction of general anaesthesia will be performed using a regimen of iv 1 μ g/kg fentanyl and propofol iv 2 mg /kg. tracheal intubation will be facilitated using 0.5 mg/kg iv of atracurium. maintenance of anaesthesia: anaesthesia will be maintained with inhaled sevoflurane with mac 2% in oxygen enriched air (fio2=0.5) and top up doses of atracurium (0.1 mg/kg) iv will be administered every 30 minutes. ringer acetate will be infused to replace their fluid deficit, maintenance and losses, and the patients will be mechanically ventilated using the appropriate setting that will keep the end-tidal co2 at 30-35mmhg. one reading of mean arterial pressure (map) and heart rate (hr) will be taken 1 minute before induction of general anaesthesia (a baseline reading), 1 minute before surgical incision and at 15-minute intervals intra operatively. lack of inadequate intraoperative analgesia, as defined by an increase in pulse rate, sweating, and tearing (prst) score \>2 or an increase of mean arterial blood pressure (map) \>20% of baseline (8) was treated by additional rescue iv fentanyl 1-2 mcg/kg iv bolus. hypotension will be treated with 0.9% normal saline and/or 5mg ephedrine in incremental doses to maintain mean blood pressure above 70 mmhg. the residual neuromuscular blockade will be reversed using neostigmine (0.05 mg/kg) and atropine (0.02 mg/kg), and extubation will be performed after complete recovery of the airway reflexes. the patient will be transferred to the post-anaesthesia care unit (pacu) where the map and hr will be recorded immediately upon arrival. side effects such as local anaesthetic toxicity, postoperative nausea and vomiting (ponv), respiratory depression (respiratory rate \<10/minute) will be recorded.

Eligibility criteria:
inclusion criteria: * physical status asa i and asa ll. * age ≥ 18 and ≤ 65 years. * body mass index (bmi): ≥ 20 kg/m2 and ≤ 35 kg/m2. * patients undergoing abdominal surgeries. * patient is able to provide a written informed consent. exclusion criteria: * known sensitivity to local anaesthetics. * significant liver or renal insufficiency. * contraindication to regional anaesthesia e.g. local - sepsis, pre-existing peripheral neuropathies and coagulopathy. * patient refusal. * failed block.